1. Modification of the rate of a periodic movement, e.g., the heartbeat, through some external influence.
2. Interference with the regularity of periodic movement; such as, the heart beat.
3. An orientation response due to age; used particularly with reference to the movement of leaves in plants.

chthonism

1. Being in, or beneath, the earth.
2. Dwelling in, or beneath, the surface of the earth.

A form of social organisms in which a member of one species steals the prey or food stores of another species to feed its own progeny: Cleptoparasitism is a relationship; such as, with some wasps, whereby the female regularly usurps the prey of the other one for purposes of rearing her own offspring.

clinotropism

An orientation response to a gradient of stimulation; also clinotropic.

clitorism

Persistent and usually painful erection of the clitoris.

clonism, clonismus

A state of successive clonic contractions or a reference to the phase of an epileptic convulsion or the type of movement occurring in this phase, usually in the form of brief muscular contractions repeated at short, regular intervals.

coalitionism

The idea, principle, or policy of favoring or supporting the concept of coalition or a specific coalition; especially, in politics.

collaborationism

The act of cooperating traitorously with an enemy who is occupying one's country.

colloquialism

1. A form of speech or phrase proper to, or characteristic of, ordinary conversation; a colloquial expression.
2. An informal word or phrase that is more common in normal conversation than in formal speech or writing.

The symbiotic (living together) relationship between two different kinds of organisms when one organism gets benefits from another organism without hurting or damaging it: "One example of commensalism is when barnacles are attached to whales."